When driving in fourth or fifth my car shakes sooo damn violently that i have to slow right down or rev high in third
Up on jack stands if i rev it in fourth or fifth/use the throttle the entire engine jumps forward and it really does jump alot. Its not the mounts as there all fine and checked. Its strange as it only does it in fourth and fifth at all revs where as third i could rev it extremely high and it wont shake at all.
Any ideas?

 

boing

 

wheels balanced up?

 

Could be gearbox fucked?? a mate of mine had the same sort of problem just in forth and fifth then one day the wheels just locked up and it got stuck in forth we ended up having to cut the driveshafts to move it